package com.zifeng.study.springbootshirojwtdemo.filter;

import com.zifeng.study.springbootshirojwtdemo.exception.UnLoginException;
import com.zifeng.study.springbootshirojwtdemo.shiro.JWTToken;
import lombok.extern.slf4j.Slf4j;
import org.apache.shiro.authz.UnauthorizedException;
import org.apache.shiro.web.filter.authc.BasicHttpAuthenticationFilter;
import org.springframework.http.HttpStatus;
import org.springframework.web.bind.annotation.RequestMethod;

import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * @author: 吴梓锋
 * @date: 2022/01/14 16:00:05
 * @version: 1.0.0
 * @description: 自定义Filter 集成jwt功能
 */
@Slf4j
public class JWTFilter extends BasicHttpAuthenticationFilter {

    /**
     * 如果带有 token，则对 token 进行检查，否则直接通过
     */
    @Override
    protected boolean isAccessAllowed(ServletRequest request, ServletResponse response, Object mappedValue) throws UnauthorizedException {

        // 判断请求的请求头是否带上 "Token"
        if (isLoginAttempt(request, response)) {
            // 请求头存在Token则进入Token校验
            executeVerifyToken(request, response);
            return true;
        }
        //如果请求头不存在 Token，直接抛出无登录异常
        throw new UnLoginException("暂无登陆状态，请进行登录!");
    }

    /**
     * 判断用户是否想要登入。
     * 检测 header 里面是否包含 Token 字段
     */
    @Override
    protected boolean isLoginAttempt(ServletRequest request, ServletResponse response) {
        HttpServletRequest req = (HttpServletRequest) request;
        String token = req.getHeader("Token");
        return token != null;
    }

    /**
     * 执行token校验
     */
    protected void executeVerifyToken(ServletRequest request, ServletResponse response) {
        HttpServletRequest httpServletRequest = (HttpServletRequest) request;
        String token = httpServletRequest.getHeader("Token");
        JWTToken jwtToken = new JWTToken(token);
        // 提交给realm进行校验，将会调用realm中的doGetAuthorizationInfo方法
        // 这里如果校验失败会抛出异常，而异常会在我们的全局异常捕获类ExceptionController中捕获
        getSubject(request, response).login(jwtToken);
    }

    /**
     * 对跨域提供支持
     */
    @Override
    protected boolean preHandle(ServletRequest request, ServletResponse response) throws Exception {
        HttpServletRequest httpServletRequest = (HttpServletRequest) request;
        HttpServletResponse httpServletResponse = (HttpServletResponse) response;
        httpServletResponse.setHeader("Access-control-Allow-Origin", httpServletRequest.getHeader("Origin"));
        httpServletResponse.setHeader("Access-Control-Allow-Methods", "GET,POST,OPTIONS,PUT,DELETE");
        httpServletResponse.setHeader("Access-Control-Allow-Headers", httpServletRequest.getHeader("Access-Control-Request-Headers"));
        // 跨域时会首先发送一个option请求，这里我们给option请求直接返回正常状态
        if (httpServletRequest.getMethod().equals(RequestMethod.OPTIONS.name())) {
            httpServletResponse.setStatus(HttpStatus.OK.value());
            return false;
        }
        return super.preHandle(request, response);
    }

}
